1. Lecture Objectives:
Learn about
Pumps and
System Curves

2. Hydronic Terms Head loss Open-loop vs. closed loop Open System
Closed System h
Pump
Chiller
Cooling coil in AHU
Pump

3. Is this open or closed system ?
Cooling towers

4. Relationship between velocity in a pipe and pressure drop
Δp ~ v2
Δp = Constant × v2
Required power (P) for the pump
P = V × Δp P –power [W],
V –volume flow rate [m3/s], v – velocity [m/s]
Δp – pressure drop [Pa]
Δp ~ v2 (Δp ~ V2 – when same pipe is used)
P ~ V × V2 – when same pipe is used
P ~ V P2/P1 = (V2/V1)3 For the same pipe
When different pipe is used for the same flow rate:
For the same
flow rate V
Reduction of D:
smaller pipe
larger pipe
Δp [Pa or ft water] D1
D2= D1/2 A1 V1 P1
A2=1/22 A1
V2=22 V1
P2/P1 = (D1/D2)4 - for the same flow rate
or 50% smaller diameter of the pipe
for the same flow rate wee have:
4 times larger velocity
16 times larger pressure drop and
16 times lager power for the pump
v [m/s or fpm]

5. Head Loss

6. Fittings

7. Pumps Raise pressure and produce flow Main type Centrifugal Example of
Turbine pump
Base mounted
Inline
Reading (textbook)
Page

8. Pump curves
NPSHR = Net Positive Suction Head Required

10. Changing Pump Speed

11. Net Positive Suction Head (cavitation)

12. Curve for Multiple Pumps

13. System Curves ∆p ∆p
A+B A B
A+B A B V A B V A B
Parallel
Serial

14. Find a system curve for this plumbing configuration

15. Primary/Secondary and Tertiary Pumping (schematics A&B below)

16. System balancing AHU1 AHU2 HC1 HC2 100 ft 1000 ft 10 gpm 2 gpm 10 ft
pump
BOILER

17. Valves Section 5-14 and 6-15 in the textbook Types Butterfly Valves
Ball Valves
Globe Valves
Three way valves

18. Valve Sizing and Flow Coefficient
Cv value:
in liter/hour or….
in Pa
Control Valve Selection For Hydronic Systems
reference:

19. Control Valve Selection For Hydronic Systems
We tried to do this:
Valve authority

20. HW2 40 ft 20 ft 20 ft 5 ft 200 ft 30 ft 30 ft 200 ft 40 ft 10 ton